Gate-all-around (GAA) field-effect transistors (FETs) like nanosheet-based devices provide better electro-static control. Thus, a GAA device architecture helps meet the requirements for further aggressive device scaling.
Input/output (I/O) devices are an important component in many circuit designs. Traditionally, I/O devices have a thick gate dielectric which is formed by thermal oxidation of silicon. However, in nanosheet-based FETs, there is oftentimes not enough room to grow a thick oxide for I/O devices, since doing so will also increase gate dielectric thickness at the logic device region which will degrade device performance.
Accordingly, techniques for forming an I/O device having a thick gate dielectric without degrading gate stack quality in the logic device region would be desirable.